tests/e2e: add cases for watcher on compacted revision when it's mix …

…version

Signed-off-by: Wei Fu <fuweid89@gmail.com>

tests/e2e/watch_test.go

@@ -32,6 +32,7 @@ import (
 	"go.etcd.io/etcd/api/v3/etcdserverpb"
 	"go.etcd.io/etcd/api/v3/mvccpb"
 	v3rpc "go.etcd.io/etcd/api/v3/v3rpc/rpctypes"
+	"go.etcd.io/etcd/client/pkg/v3/fileutil"
 	clientv3 "go.etcd.io/etcd/client/v3"
 	"go.etcd.io/etcd/tests/v3/framework/config"
 	"go.etcd.io/etcd/tests/v3/framework/e2e"
@@ -390,6 +391,94 @@ func TestVerifyHashKVAfterCompact(t *testing.T) {
 	}
 }
 
+func TestVerifyHashKVAfterCompactMixVersion(t *testing.T) {
+	if !fileutil.Exist(e2e.BinPath.EtcdLastRelease) {
+		t.Skipf("%q does not exist", e2e.BinPath.EtcdLastRelease)
+	}
+
+	tests := []struct {
+		compactedOnTombstoneRev bool
+		hashKVOnCompactedRev    bool
+		consistentHash          bool
+	}{
+		// The test performs compaction on tombstone revision.
+		// The tombstone revision is always larger than last compacted revision.
+		// So, both versions take the same hash value in compaction.
+		{
+			compactedOnTombstoneRev: true,
+			hashKVOnCompactedRev:    true,
+			consistentHash:          true,
+		},
+		// The test performs compaction on tombstone revision.
+		// For v3.5 version, the tombstone revision has been deleted so that that revision won't be included in new hash value.
+		// For main branch, even if the tombstone revision still exists,
+		// the tombstone revision is smaller that last compacted revision and the index.Keep(hashOnRev) won't keep it.
+		// So, main branch won't include the tombstone revision in new hash value as well.
+		// Both versions take the same hash value from HashKV.
+		{
+			compactedOnTombstoneRev: true,
+			hashKVOnCompactedRev:    false,
+			consistentHash:          true,
+		},
+		// FIXME(fuweid):
+		//
+		// The test performs HashKV on tombstone revision.
+		// For v3.5 version, the index.Keep(tombstoneRev) returns empty.
+		// So, the last compacted revision will be included in new hash value again.
+		//
+		// However, for the main branch, the index.Keep(tombstoneRev) returns one revision.
+		// So, the last compacted revision won't be included in new hash value.
+		// It caused inconsistent hash value.
+		{
+			compactedOnTombstoneRev: false,
+			hashKVOnCompactedRev:    true,
+			consistentHash:          false,
+		},
+		// The test performs HashKV on non-tombstone revision.
+		// The index.Keep(non-tombstone-revision) always returns non-empty result.
+		// Both versions won't include last compacted revision in new revision.
+		{
+			compactedOnTombstoneRev: false,
+			hashKVOnCompactedRev:    false,
+			consistentHash:          true,
+		},
+	}
+
+	for idx, tt := range tests {
+		t.Run(fmt.Sprintf("#%d", idx), func(t *testing.T) {
+			verifyHashKVAfterCompactFn(t, e2e.QuorumLastVersion, func(t *testing.T, cli *e2e.EtcdctlV3, lastRevision int64, tombstoneRevisions []int64) {
+				ctx := context.Background()
+
+				hashKVOnCompactedRev := lastRevision
+				if tt.hashKVOnCompactedRev {
+					hashKVOnCompactedRev = tombstoneRevisions[len(tombstoneRevisions)-1]
+				}
+
+				compactedOnRev := tombstoneRevisions[len(tombstoneRevisions)-1]
+				if !tt.compactedOnTombstoneRev {
+					compactedOnRev = hashKVOnCompactedRev - 8
+				}
+
+				t.Logf("COMPACT rev=%d", compactedOnRev)
+				_, err := cli.Compact(ctx, compactedOnRev, config.CompactOption{Physical: true})
+				require.NoError(t, err)
+
+				t.Logf("HashKV on rev=%d", hashKVOnCompactedRev)
+				resp, err := cli.HashKV(ctx, hashKVOnCompactedRev)
+				require.NoError(t, err)
+
+				require.Len(t, resp, 3)
+				require.True(t, resp[0].Hash != 0)
+				t.Logf("One Hash value is %d", resp[0].Hash)
+
+				require.Equal(t, tt.consistentHash, resp[0].Hash == resp[1].Hash && resp[1].Hash == resp[2].Hash,
+					"Expected consistentHash = %v, but got %d - %d - %d",
+					tt.consistentHash, resp[0].Hash, resp[1].Hash, resp[2].Hash)
+			})
+		})
+	}
+}
+
 // verifyHashKVAfterCompactFn will generate 3 tombstones on key foo.
 func verifyHashKVAfterCompactFn(
 	t *testing.T,